In electric machines, commonly electrically conductive bars are used for the stator or the rotor. The conductive bars are accommodated in notches usually milled into the stator or rotor body. The conductor bars, sometimes having a drilled arrangement of the leads and then referred to as Roebel bars are insulated for high voltages when used in the technical field of generators. The insulation layers at the conductor bars often are composed of three components of which mica is the main component. Mica has a relatively low thermal conductivity of approximately 0.5 W/mK in the axial (normal-to-plane) direction, thus limiting the heat transfer within the entire insulation composite. The mica also governs the coefficient of thermal expansion (CTE) of the insulation in the in-plane direction, forcing it to a CTE of approximately 10×10−6 K−1, which is substantially lower than the CTE of the copper conductor. Hence, there is a need for an alternative electrical insulation material that has higher thermal conductivity and CTE.
EP2102968A1 describes a conductor bar for the stator of a generator which includes multiple internally positioned partial conductors which are surrounded externally by an insulation layer including impregnated glass/mica bands wound around the partial conductors. To improve the mechanical adhesion between the partial conductors and the insulation layer, at least one intermediate layer is provided between the insulation layer and the partial conductors.
An aspect of embodiments of the present invention is to provide an alternative insulation material in the field of electric machines.